|
Some of these posts are very old and might contain outdated information. You may wish to search for newer posts instead.
|
Kizzle
Misanthrope


Registered: 08/30/11
Posts: 9,866
Last seen: 3 months, 19 days
|
The Truth About Cobweb 7
#18642418 - 08/01/13 02:35 AM (10 years, 10 months ago) |
|
|
This has been long overdue, I'll start by explaining what led me to post this. I've been growing mushrooms for a good 4+ years but not until fairly recently, after assisting with the culitivation of Agaricus bisporus, did I start to suspect that what I had always considered cobweb mold may actually be something else. Unlike the competitor molds you're used dealing with cobweb mold is a mushroom pathogen. It's occurrence is in no way linked to contaminated spawn and is rarely a problem in bulk substrates. To ignore that and misidentify other molds as cobweb is counterproductive to determining the source of contamination problems and what to do about them. In trying to make sense of contradicting information I've read a huge amount of information from books, published studies, experiments, etc and thought I'd share some of it.
just to clarify things up front, the term cobweb mold is often used loosely to refer to any kind of thin whispy grey mold and that's not what I'm referring to. Hopefully I can help distinguish the difference between these molds and the specific mold that causes cobweb disease.
To start, cobweb mold could be defined as a group of closely related species capable of causing cobweb disease in mushrooms. Many of these species are so similar they can only be properly identified from each other through genetic testing. They've been reclassified over the years, and as is often the case in taxonomy not necessarily with complete agreement among mycologists, so you may hear different species or names mentioned. In the US Dactylium or the species Dactylium Dendroides is usually referred to as the causative agent. In eastern countries you'll more commonly hear them referred to as various Cladobotryum spp. I also note the Shroomery main site mentions Hypomyces sp. which is also correct. In fact Dactylium, for the most part, is synonymous with Hypomyces Rosellus.
Cobweb mold grows on casing layers and mushrooms. Although in theory it could occur on any uncolonized substrate so long as a suitable host is present, it's been shown experimentally that neither spores or mycelium fragments added to spawn will result in development of cobweb disease, nor does adding them to the surface of bulk substrate substrate during spawning, even when a casing layer is then added over it.
Cobweb mold spreads quickly. This is absolutely true, but it's rarely mentioned that the primary reason for this is it's ability to fragment and start growing from multiple points on the casing layer and not solely from the growth speed of a single colony. The growth rate is closely tied to the environmental conditions it is growing in. This is important for two reasons. A slower growth rate may be wrongfully assumed to rule out cobweb during identification. It's also important because changing these conditions can assist in dealing with an outbreak assuming the mushroom species being cultivated is able to tolerate the changes. Lowering temperature and/or RH can slow the growth of cobweb mold or even inhibit it completely.
Cobweb is usually seen in later flushes. IMO this is important to consider both in terms of identification and in finding the source of the contamination. Cobweb proliferates mostly by means of spore. Even high amount of spores added directly to a casing layer requires weeks before the first sign of cobweb disease occurs. With that in mind any the appearance of actual cobweb mold in earlier flushes is most likely the result of mycelium fragmentation and that strongly implies a nearby source. This appears to be true despite the fact that the mold spores can germinate much more quickly on an actual fruit body.
Mushroom stumps are a common point of origin. Now before anyone freaks out and reverts to twist-and-pull, this has nothing to do with the stumps rotting. A cobweb infected mushroom, whether apparent or not, may leave behind a cobweb infected stump.
Aborts are an even more common point of origin. This does not mean aborts need to be picked immediately but they should always be removed while harvesting your other mushrooms. That can be a painstaking task if there is a very large amount of aborts.
This is really open to interpretation. There's definitely a correlation between cobweb disease and aborts but it's hard to say if the aborts are cause of the mold or if the mold is the cause of the aborts. Considering the same conditions that can lead to a lot of aborts can lead to mold contamination... 
There are many look-alikes. I find it frustrating how quick people are to identify any fuzzy or grey mold as cobweb mold regardless of where or how it's growing. Pin molds, called that because of the black pins which they may produce, are commonly misidentified as cobweb. In contrast to cobweb, which occurs in the casing laying, pin molds are very common contaminants in spawn and some bulk substrates. In ideal conditions some species can grow at rates matching or surpassing those of cobweb. Despite their somewhat similar appearance these molds are far more difficult to treat and misidentification has apparently left some with the impression that actual cobweb mold is hard to treat.
Cobweb is easily treatable. A common misconception is that hydrogen peroxide only affects cobweb mold. Perxoide will react in some way or another with pretty much any fungus, including mushroom mycelium. The most common reaction to fungi is fizzing caused by the rapid conversion of h202 into water and oxygen bubbles. The fact that cobweb grows solely on the casing surface is what makes it easier to treat than other molds.
On a personal note, despite claims I find it increasingly hard to believe peroxide could be an effective treatment of actual Cladobotryum considering it's ability to grow inside the mushroom. It certainly doesn't match my own experiences nor have I seen any studies to support it nor any claim accompanied by documentation showing the mold could indeed be positively identified (visible spores, cobweb disease present). Whether this is due to misidentification or just differences in tolerance between strains/species I'm uncertain.
However I confirm in cases where cobweb disease is present it can be controlled by placing a damp paper towel over the growth and pouring salt over it, and by removing mushrooms showing spotting symptoms. Some may be hesitant to try this, just keep in mind you're salting the casing layer, the damage to the mushroom mycelium is relatively small and there plenty of other areas for mushrooms to develop. That's part of the reason BTW Trichoderma almost always reoccurs once it's been growing in the spawn, Trich originating on a casing layer is much easier to treat.
Of course no rambling of this nature would be complete without a RR quote.
Quote:
Cobweb mold is the only thing you can totally kill and eliminate with peroxide. Nobody has lost a project to cobweb mold who has made searches here to find the cure. You're supposed to spray it until wet three times at 12 hour intervals. Spray until all the cobweb mycelium has 'melted' and disappeared. Repeat twice at 12 and 24 hours after the first spray whether you see any cobweb or not.
RR
Overall cobweb disease does not appear to be particularly common with Cubensis, certainly not as common as many believe. Probably because most Cube cultivators do not use casing layers or use pasteurized casing layers. Spores of Dactylium are killed when exposed to 115-122°F. for only 1/2 hour making it extremely unlikely to survive pasteurization. It's uncommon but possible for mushrooms to get the disease even without a casing layer. It such a situation the mold mycelium will not grow on the fully colonized substrates surface but may still be seen spreading to nearby pins and mushrooms directly.
Some miscellaneous info:
A particular species may produce different or no symptoms of the disease depending on the mushroom species being grown.
According to one source C. Dendroides produces a noticeable odor while C. Mycophilum does not.
Spores will not become airborne early on in it's development unless the colony is physically disturbed, like while misting.
Spores are relatively massive. In the presence of typical air currents most spores will have settled after 15 minutes.
Spores survive a maximum of 7 days in sterile water.
Heavy spore production occurs usually occurs near and on infected mushrooms.
In time, some species produces metabolites which turn the mycelium and/or substrate a pink or yellow color.
When the disease is allowed to progress the mycelium will take on a powdery appearance from the produced spores.
The following are pictures positively identified by reliable sources.
 Spore production on 2 cobweb infected mushrooms
 Another good one

A culture of C. mycophilium. Spore are visible here as well on the top left.
 An untreated outbreak in the late stage
 This was from a study although the quality limits it's usefullness. The symptoms of 2 different species cobweb isolated from 4 different source inoculated into 4 different mushrooms species.
 The appearance on agar of 2 different cobweb species isolated from 4 different mushrooms.
 The effects of temperature on growth
 Infected mushroom
 Close up of stem
 Cladobotryum mycophilum
 Cladobotryum variospermum
Here are some pictures of cobweb on Cubensis which I should mention to my knowledge have not been identified beyond all doubt.
 Possible cobweb on partially colonized substrate. It's growing completely over the substrate and not over the mycelium.
 Cobweb on the (supposed to be) dry verm layer of a BRF cake. It's no coincidence that it didn't appear until the mushroom mycelium had grown through. That is a necessary for any visible growth on a casing layer, or in this case the equivalent of a casing layer. You can see the powdery of what appears to be spore formation.
 You can't even see them all anymore but there are pins and primordia under all those patches towards the bottom. However no spores for confirmation.
 Cobweb on harvested mushrooms
Some things that are NOT cobweb
 A perfect example of a pin mold which was thought to be cobweb despite the obvious presence of the black pins, and the immature white pins.
 Verticillium infected mushroom
 Mushroom mycelium (fuzzy feet)
 Old mushrooms and stumps although if there was cobweb there I don't think anyone would notice 
If anyone has anything to add or correct feel free to do so.
Quote:
On a personal note, despite claims I find it increasingly hard to believe peroxide could be an effective treatment of actual Cladobotryum considering it's ability to grow inside the mushroom. It certainly doesn't match my own experiences nor have I seen any studies to support it nor any claim accompanied by documentation showing the mold could indeed be positively identified (visible spores, cobweb disease present). Whether this is due to misidentification or just differences in tolerance between strains/species I'm uncertain.
UPDATE: It's been a while since I posted this. I think I can say without a doubt now that actual Dactylium is not killed by 3% hydrogen peroxide. I have however discovered there are a couple Mucorale(pin molds) species that are when growing in anaerobic conditions. Or in other words they grow when gas exchange is lacking or when the substrate is oversaturated with water. They also do not sporulate under those conditions so if you're seeing the black pins they've establish themselves well enough to compete with the mushroom mycelium even after conditions are fixed and you've most likely already lost the opportunity to fix the problem.
Edited by Kizzle (07/13/15 08:28 PM)
|
Jimmyhunter1000
That guy.



Registered: 06/15/12
Posts: 777
Loc: Massachusetts, USA.
Last seen: 6 years, 2 months
|
Re: The Truth About Cobweb [Re: Kizzle]
#18643408 - 08/01/13 11:20 AM (10 years, 10 months ago) |
|
|
Always informative as usual Kizzle. Cobweb is a term that's very commonly thrown around here that needs to be understood much better. I'd love to see some more pictures added to this of other commonly cultivated mushrooms infected with it. There's a guide about Trich, so why not one about Cobweb!
-------------------- There isn't a trail too long or too wide.
Edited by Jimmyhunter1000 (08/01/13 11:21 AM)
|
Kizzle
Misanthrope


Registered: 08/30/11
Posts: 9,866
Last seen: 3 months, 19 days
|
|
I was hoping to get some discussion. Some of what I posted directly contradicts what some people have been saying. I wouldn't mind hearing their opinions it. I've just been looking for facts to back up certain claims.
--------------------
Edited by Kizzle (08/05/13 05:41 PM)
|
Psilicon
Really Nice Guy


Registered: 08/26/12
Posts: 7,057
Last seen: 3 years, 6 months
|
Re: The Truth About Cobweb [Re: Kizzle]
#18674319 - 08/07/13 04:30 PM (10 years, 10 months ago) |
|
|
Wow, thanks for putting this excellent write-up together. I'll be linking to it frequently over in cultivation.
|
juanh74
Stranger
Registered: 08/10/13
Posts: 13
Last seen: 10 years, 10 months
|
Re: The Truth About Cobweb [Re: Psilicon]
#18712294 - 08/15/13 11:26 PM (10 years, 10 months ago) |
|
|
Priceless info, ill keep it close if I encounter anything like it in my up-coming cultures.
|
Mycjunky
Stranger


Registered: 07/25/09
Posts: 1,837
Last seen: 4 years, 18 days
|
Re: The Truth About Cobweb [Re: Kizzle]
#18712903 - 08/16/13 03:02 AM (10 years, 10 months ago) |
|
|
Interesting post. Can't say I've run across cobweb except for in extreme cases where things weren't being maintained. It's always trich for me on fruiting sub.
|
Terry M
Stranger in a Strange Land



Registered: 06/18/10
Posts: 1,502
Loc: Rhode Island
Last seen: 9 years, 5 months
|
Re: The Truth About Cobweb [Re: Mycjunky]
#18718088 - 08/17/13 08:15 AM (10 years, 10 months ago) |
|
|
Great post! Similarly, much Trich identification can be other contaminants instead. I see Penicillium commonly reported as Trichoderma.
-------------------- Liberté, égalité, humidité.
|
Kizzle
Misanthrope


Registered: 08/30/11
Posts: 9,866
Last seen: 3 months, 19 days
|
Re: The Truth About Cobweb [Re: Terry M]
#18785822 - 09/01/13 03:35 PM (10 years, 9 months ago) |
|
|
Despite my best efforts I've been unable to find any pictures of Cubensis with a visible sporulating cobweb mold infection nor have I been able to isolate any cobweb species from Cubensis showing any of the possible symptoms. I'm really starting to doubt the occurance is anything but rare on Cubensis. It's pretty well known that it's uncommon on some mushrooms like oysters, so frankly it wouldn't surprise me if that were the case.
--------------------
|
OUboundMycologist
Student Pharmacist


Registered: 09/15/13
Posts: 49
Loc: USA
Last seen: 9 years, 11 months
|
Re: The Truth About Cobweb [Re: Kizzle]
#18975071 - 10/14/13 02:40 AM (10 years, 8 months ago) |
|
|
So what do I do if I see cobweb on EVERYTHING after 3-5 days? I was thinking that it was because I lived in an old house but after reading your post I guess I was mistaken...
So correct me if Im wrong, BUT you are saying that cobweb ONLY grows in the presence of mushroom mycelium? Is it just that the mycelium is monokaryotic and invisible?
Ive been told that Hydrogen Peroxide kills spores as well so if theres cobweb growing in a petri dish on agar can I make some lower H202 solution to kill the cobweb but not my spores?
-------------------- "Be the change that you want to see in the world" Anything illegal or that has to do with mushrooms that I talk about is completely 100% fictional and is not true.
|
Kizzle
Misanthrope


Registered: 08/30/11
Posts: 9,866
Last seen: 3 months, 19 days
|
|
On a casing layer cobweb requires a host fungus as a source of nutrients to produce visible amounts of growth. Something I'm trying to stress is there are lot of molds other than cobweb that look similar but have different characteristics so in many situations where people are assuming they have cobweb mold it's actually a different mold.
Cobweb can grow in a petri dish although the type of growth will vary drastically depending if it was inoculated simply with cobweb spores with no other fungi in the dish or say cobweb mycelium transferred with a piece of a contaminated fruit body.
Peroxide can be lethal to mushroom spores and toxic to mushroom mycelium so the best option is to try and isolate healthy mushroom mycelium by transferring it to a different dish.
--------------------
|
Snktido
Stranger

Registered: 11/16/13
Posts: 30
Last seen: 10 years, 3 months
|
Re: The Truth About Cobweb [Re: Kizzle]
#19276863 - 12/14/13 10:32 PM (10 years, 6 months ago) |
|
|
The survival stress level temps for cobwebs are said to be in the 60-65 range. Since fridge temps are much lower, has anyone ever cured their infected sample by simply refrigerating it for a period of time?
|
Kizzle
Misanthrope


Registered: 08/30/11
Posts: 9,866
Last seen: 3 months, 19 days
|
Re: The Truth About Cobweb [Re: Snktido]
#19280110 - 12/15/13 04:32 PM (10 years, 6 months ago) |
|
|
Growth temperature maybe. I don't think that would kill any fungus.
--------------------
|
Snktido
Stranger

Registered: 11/16/13
Posts: 30
Last seen: 10 years, 3 months
|
Re: The Truth About Cobweb [Re: Kizzle]
#19281214 - 12/15/13 08:44 PM (10 years, 6 months ago) |
|
|
I did some more research on the topic and found a good article. I do not think any of it contradicted anything you said. Anyhow here is what I got from it.
-"The development is characterised by typical colour changes from creamy white (+ 4 days) to yellow (+ 9 days) to pink (+ 12 days) and finally to red"
- "Microsclerotia... have only been observed in axenic (sterile) cultures" Found only in Sterile cultures? Meaning it originates from the host composition?
- "majority of spores are dislodged and carried by air movement... spores are quite large and aerodynamic and easily disintegrate. In order to transport spores a minimum airspeed is necessary... airspeed of 0.1 m/sec was insufficient to dislodge cobweb mould spores and transport them over any great distance" Stating at that speed they can still be airborne.
- "The optimal temperature for spore development is 25 degrees Celsius. If treated for 30 minutes the temperature required to destroy Hypomyces rosellus spores is 43 degrees Celsius... RH lower than 85 % very few spores germinate"
-" optimal temperature for mycelium growth is 20 degrees Celsius"
-"Encouraged by Mushrooms and stalks left on the beds; high temperatures; high RH and too moist casing soil layer."
source - http://www.mushroombusiness.com/content/articles/detail/268/cobweb-disease-an-overview
|
Snktido
Stranger

Registered: 11/16/13
Posts: 30
Last seen: 10 years, 3 months
|
Re: The Truth About Cobweb [Re: Snktido]
#19281333 - 12/15/13 09:11 PM (10 years, 6 months ago) |
|
|
I have also read that people with plants in the house tend to get cobweb mold contamination at higher rates than non plant owners. This is due to the fact that cobweb mold exist naturally in soil and are spread around the house via air current.
Also mentioned on ehow.com, gardenguides.com, and other places -"Cobweb mold thrives in high temperatures and dies when temperatures drop lower than 65 degrees"
This suggest that temps lower than 65 degrees F will kill cobweb mold. However this does not necessarily mean that it will kill the spores if it has been already produced. Thus Peroxide is the cure for spores. In addition, to simply weaken the fitness the of cobweb mold will be enough for your mushroom mycelium to take over and eliminate it by natural process. This only is so if your mushroom mycelium have sufficient access to the invading cobweb. (reference needed)
|
Snktido
Stranger

Registered: 11/16/13
Posts: 30
Last seen: 10 years, 3 months
|
Re: The Truth About Cobweb [Re: Snktido]
#19281349 - 12/15/13 09:14 PM (10 years, 6 months ago) |
|
|
Spores are why it is common practice to work in a zero or minimal turbulent air environment and spray the room down with a fine mist of bleach+H2O mixture prior to substrate inoculation.
Well that's my 2 cents.
|
sparkle
Farmer



Registered: 07/28/11
Posts: 1,133
Loc: Philippines
|
Re: The Truth About Cobweb [Re: Kizzle]
#19818678 - 04/09/14 02:38 PM (10 years, 2 months ago) |
|
|
Sorry to dig up an old thread but I really need help. We're trying a new protocol using these big bags. This is an 8 kilo Calocybe Indica spawn. This pic was taken 2 days ago and this bag is now almost fully colonized. The problem is in 2 tiny spots there is cobweb hairs clinging to the plastic. My question is can I still plant this to bulk? We've never had a problem with cobweb on our fruiting beds although I'm sure it would sometimes be there.
|
Kizzle
Misanthrope


Registered: 08/30/11
Posts: 9,866
Last seen: 3 months, 19 days
|
Re: The Truth About Cobweb [Re: sparkle]
#19820479 - 04/09/14 08:26 PM (10 years, 2 months ago) |
|
|
Looks alright to me. Although I can't actually see the spots you're talking about most if not all mushroom species are capable of doing that. The mycelium is sort of attracted to the condensation that forms on the plastic.
--------------------
|
Ecuador
Stranger



Registered: 05/10/11
Posts: 12
Loc: Brazil
|
Re: The Truth About Cobweb [Re: Kizzle]
#19822261 - 04/10/14 07:04 AM (10 years, 2 months ago) |
|
|
Quote:
Kizzle said:Something I'm trying to stress is there are lot of molds other than cobweb that look similar but have different characteristics so in many situations where people are assuming they have cobweb mold it's actually a different mold.
Any idea about what are these cobweb-like molds, Kizzle?
|
Kizzle
Misanthrope


Registered: 08/30/11
Posts: 9,866
Last seen: 3 months, 19 days
|
Re: The Truth About Cobweb [Re: Ecuador] 1
#19825728 - 04/10/14 09:03 PM (10 years, 2 months ago) |
|
|
Mucor and Rhizopus are probably the most common. They are common contaminants of grain spawn and BRF substrate and grow very quickly. If you ever see a cake do this one of those is likely responsible.
I've given up on trying to convince people not to call these cobweb mold, at least on the shoomery boards, but they certainly don't cause cobweb disease and aren't what traditionally is considered to be cobweb mold.
--------------------
|
Psilicon
Really Nice Guy


Registered: 08/26/12
Posts: 7,057
Last seen: 3 years, 6 months
|
Re: The Truth About Cobweb [Re: Kizzle] 1
#19825885 - 04/10/14 09:38 PM (10 years, 2 months ago) |
|
|
IMO this thread is great (I think I five-shroomed you for it), but if you're going to spread the gospel of this-is-not-cobweb and have it stick in cultivation you're going to have to give them something colloquial to call it. Furball, maybe?
|
|